Copyright © 2008 The Institute of Electronics, Information and Communication Engineers
Regular Section -- Papers -- Wireless Communication Technologies |
IP Packet Loss Prevention Scheme with Bicast and Forwarding for Handover in Mobile Communications
1 The authors are with the Faculty of Science and Technology, Keio University, Yokohama-shi, 223-8522 Japan. E-mail: saito{at}nkgw.ics.keio.ac.jp, 2 The author is with the Radio Access Network Development Department, NTT DoCoMo, Inc., Yokosuka-shi, 239-8536 Japan. E-mail: morimotoa{at}nttdocomo.com
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Abstract |
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This paper proposes a scheme for hard handover (HO) between base stations (BSs) that combines bicast with forwarding; it realizes packet-lossless HO as well as low HO control delay. The proposed scheme observes the status of the current channel condition and initiates bicasting, the simultaneous transfer of IP packets from the access router to both the old BS and the new BS, when the probability of HO becomes high; this reduces the control delay imposed by hard HO. When HO becomes unavoidable, only those IP packets remaining in the old BS buffer that are not shared with the new BS are forwarded to the MS; this prevents the loss of IP packets. Computer simulations show that the proposed scheme reduces the HO control delay at 95% cumulative distribution function (CDF) by approximately 1700 (300) msec, 340 (320) msec, and 170 (330) msec compared to the conventional forwarding scheme (the conventional bicast scheme) when the number of users is 80 and the maximum Doppler frequency (fdmax) is 5.55 Hz and data rate (D) on the wired propagation channel is 10, 50, and 100 Mbps, respectively. The results confirm the superiority of the proposed scheme as an IP packet loss prevention scheme for hard HO.
Key Words: hard handover, bicast, forwarding, IP packet
Manuscript received March 28, 2006. Manuscript revised March 17, 2007.